Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 23: TR: Quantum Coherence and Quantum Information Systems 2

TT 23.6: Vortrag

Mittwoch, 24. März 2010, 15:30–15:45, H18

Coupling of a quantum oscillator to a superconducting flux qubit at its symmetry point — •Pascal Macha¹, Arkady Fedorov², Alexey K. Feofanov³, Pol Forn-Diaz², Evgeni Il’ichev¹, Alexey. V. Ustinov³, Kees Harmans², and J. E. Mooij² — ¹Institute of Photonic Technology, Jena, Germany — ²Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands — ³Karlsruhe Institute of Technology, Germany

Resonant coupling of a quantum oscillator (ℏ ω > k_B T) in the low–photon limit to a flux qubit at its symmetry point provides optimal conditions for the realization of cavity-QED experiments, i.e. long coherence times and the largest qubit–oscillator coupling. We report an experiment demonstrating this regime using the recently developed tunable gap flux qubit [1]. The control over the energy barrier height enables us to tune the gap of the flux qubit in and out of resonance with a superconducting LC resonator. We performed spectroscopic measurements of the qubit–oscillator system and demonstrate vacuum Rabi oscillations for various representative cases. We find that the decay time of these oscillations for the qubit operated at its symmetry point is not affected by 1/f flux noise and is only limited by the quality factor of the resonator. This work contributes to the development of advanced quantum information processing schemes with superconducting qubits.

[1] F. G. Paauw, A. Fedorov, C. J. Harmans, and J. E. Mooij, PRL 102, 090501 (2009)